I have replaced the battery and badly corroded positive cable. The car runs fine but if the revs get over 2k ALL lights go out. So far the car hasn't stalled and lifting off the throttle eventually gets the lights back on. When the lights go out I can hear a switch click under the center right side of the dash.

I've had the charging system tested at the local parts store and everything is "fine". There are no fault codes. PLEASE HELP!

 

Did they check the system over the problem area of 2000 rpms?

 

I'd look at the passenger floor carpet first- if its wet, the dreaded wet 'Smart Junction Box' can screw everything up... clogged cowl drains are #1, and side window trim gasket squeezing out #2, the 'grommets' where the cowl trim panel snaps into base of windshield #3... any of those lets water run over the SJB, and weird stuff happens- quite a few 'first noticed' indications are weird taillight patterns- if the thing gets wet, it turns random outputs on/off, most folks dried theirs out and no further problems. mine had cowl drain plugs clog(no issue except wet floor/SJB) and 2 yrs ago I replaced the window trim gaskets(it was oozing out both sides near the rearview mirrors) and it caused a VERY wet floor/SJB after driving in a heavy rain - again, dried it up no issues... I havent done my cowl cover grommet sealing yet, maybe over winter- know its going to eventually leak there too...

the passenger kick panel is easily removed, just pop it out and look for any drops of water around the SJB/plugs...if wet, unhook batttery, remove, dry out... I found if the carpet is wet, you REALLY must pull the carpet up to dry it- theres a rubber pad under that might let carpet dry, but leave a wet steel floor to mold/stink/rust...I didnt pull it clear out, just took doorsills up, lifted carpet and blocked, lifted rubber pad/blocked, left doors open 3 days with dehumidifier blowing thru in the garage... the water sealing issues with these cars is a bit irritating, Ford REALLY dropped the ball in the cowl/a-pillar/cowl trim grommet design

 

Thanks AZPete! I guess thats the difference between a good parts store employee and a bad one.

The alt was overcharging te battery. Quick waranty swap-out and all is good!

 

Glad you got it fixed....